Telephonic apparatus



Feb. 12, 1935. R. T. KINGSFORD TELEPHONIC APPARATUS Filed May 17, 1930 2 Sheets-Sheet 1 iwwlu k 151 flZZ'OPTB-QEK Feb. 12, 19435. R. 'r. KINGSFORD TELEPHONIC APPARATUS Filed May 17, 1930 2 Sheets-Sheet 2 u rllll wflllfl Patented Feb. 12," l

- Atwater Kent Manutacturing'cqmpany, Phila-' My invention relates to telephonic apparatus, particularly for loud-speaking purposes, comprising a diaphragm to' which-is attached a vi- 1 bratory voice-current coil disposed in a magnetic -field, produced either by a permanent,;;or, preferably," byl-an: electro-magnetl 1 Inaccordancel; th'my invention, the lead or connection frompthe voice coil; to' the external circuit takes off, to a fixed, terminal. directly" from the coil-form, or support, without attachment "to andentirely independently of the diaphragm,

" lhe leader connection l.which may be a con Itinuationpfthe coil conductor ritselflor "some stantially in fixed position-withrespect to'the coil-rormor support, moves or-fvibrat'es withan amplitude which is thatof the vibrations of the 1 coil and its supporta i Furtherin accordance with-"my invention; when the vibratory;- diaphragm is of vthe conical or thereto by 3 anyjsuitable means and the anchorages ortake offs of the flexible'coil leads areat I ppintsupon and fixed with-trelation to the coil' -3o support or formbetween the diaphragmand the coil and for this purpose the coil-form or support is sufficiently long between thecoil and diaphragm to permit full or maximum YVibI'atiOII of the :coil

anchorages or take-offs :to. the pole structure of the magnetic field of the instrument as to cause the leads yunderaany cireumstances oiv. use} too closely to .approach ior contaoti-withtthe pole structure. 1

My invention resides in structure, and in features of arrangement and, proportionment, here- 1 mm" q sq d'a ducla m For an illustration of; some of 1 the various forms my v i nmay taker reference; is :to .be had Wi accompanying, dra in s'; in, whichr: i a;

n "Fig. 1 is a verticalsectional view,":partly -in e1evation, y of loud] speaking; telephonic apparatus embodyingmyinventiomwj l Fig. lboniyenlargediscale.

effecting attachment of jthe diaphragmfito the coil-former support; i

"invention;

equivalent type of large diameter for direct action ing at its without such close'approachfi theleads or their l TEL rnomo mamas Pennsylvania scale, of a mwmeaiom or coil support-or spool and its attachment to the-diaphragm;

Fig. is'a sectional View of a diap'hragm in tegral with the'coilspool or form.

Fig.5 is affragmentary se conical dia hrag ling niy inventionf o y W i l Fig-fiflis ayerti'cal sectional view; parts in elevation, of a cone-type ctionalview of alar'ge m' and its actuatingcoil embody- D- T SP TEN OFF CE!* loudspeaker embodyingrny i Fig. 8 is" a fragmentary"diagrammatic viewf of 1 anamplifier system utilizable'for supmymg soundrepresenting current to the' voice'coili Y Referring-toFig.--I,P is a pot or'ca I cylindrical or other suitableyformationg of iron or other suitable magneticumaterial, having a bottom 1 of like 'materialin or :to" which is attached the central'magnetizabl'e core Z tern inattion tothe exciting source. g

' 1The:outer.cylindrical surface of the pole I is one boundary of an'airgap whose other boundary is ;,the inner cylindrical surface of an" aperture upper end in the cylindrical inner pole piece I. Surrounding the l-pole2 is the field or energizing =coil' C traversed by direct "current; as

frorria storage battery, 1 orby rectified alternat ing current; or equivalent. The leads 3, iirom 1 the terminalsof the coil- G extendto the exterior r .y n 30 "of-the pot Pthrough the aperturewoior connec- 7 in the "outer nmagnetizabletpolej plate 0 secured 4301 thexpotby screws '6 In 'the air-1=gap between the polesl and} Q is disposed fthe spo'ol support or form Eupon whichiswound the coil S, in one lrori' more layers, traversedfby sound-representing r current, :the combinationkof f the coil Shw'ith 1 the magneticifield"structure-*constituting an electroo dynamic system. I-he coil forriilF ofbakelite, paper, or other suitab1e material; is attached to the vdiaphragm' faDioff Lm'ica, ising1ass; -rnetal or other-suitable material; by "the member "or spider i z ofanyi-suitabl'e material such as sheetahim'inurn v i I or other metal; 2 is a vert'cal. sectional view, on the line 2--2-,of 1 Fig, 211,1 partly: in elevation; of parts of u Secured to the pole plate 1 O'by screws is aZ=dish-'shapedlplate 58. to; which is" se orrother'suitable i material which holds the outer :edgef'or' peripheryof the diaphragm D Enclosing the diaphragm and itsmounting is the -m'embfer :12 of: brass '01 the like", secured by screws 6, and

, and abutting provided with a circular channel in which may be disposed a rubber tubing gasket 13 engaging the plate 10. In the'member 12 above the diaphragm is a sound passage 14 with which registers the small end'15 of a horn or the like resting in a socket in the upper end of the member 12.

Referring more particularly to Figs. 2 and 2a, illustrative of parts. comprised in ,Fig. 1, coil form F is shcwm asihauing a peripheral channel in which is wound the voice coil S. The spider Z has a flange. 16 extending outwardly from the cylindrical portin17 fitting within the form F;

tion 18 having at its center a hole: 19" through which and the diaphragm D extends the-rivet,-

' screw or equivalent element 20 whereby-the coil S ment 23 which, in the is fixed to the diaphragm D for vibrating it in accordance with! the sound-representing" current traversingithecoil-fl The portion 18 may be pro.- vided, with one or more. openings 21 to lighten the structure, and alsa facilitating application of the leads, as will now be described. Adjacent an opening. 21. in: the sp der is a-hole-zz extending through the wall of the f0rm- F1 adjacent, the

:flange 1.6-.- There extends: through this hole" to the interior of thefcrm F the lead-yhof any suitable conducting material such as a flexible or braided lead solidjwire er the like. H On the inner endof the lead L.-

produced, a. head or' enlargeexample illustrated, is a The enlargement 23' is larger thereby preventinggthe lead'L knot the lead Ll, than. the hole 22",.

from pulling outwardlytherethrough. 'I'h-rough ahole 24eneend of; the conductor s,1 forming the winding. 8-,. islet intdthe interiorofi the form E,

and thn indieatedr the wi l cenductor extends through.- the hole 22 to the exterioriof form F and; is-there wrapped. around: the lead: L: and

in all soldered. thereto .at;.-25 thus completing the anchorage of. lead LL Suitable cement may be applied around the-cenlargement 23, or around the joint 25;, or botlm. to prevent rattling of the lead' L in the coilform;

While in the exa-p pleiill-ustrated the lead L1 is not, ing a structural sense; a continuation of the conductor of the coil S, it shall: be understood that cases herein1,describ ed, it may be;v ,In the present example the conductor of'the coil Simay itself extend from the-..imside of the form I? to the outside or the hole 22. and. thence; onwardly to the fixed-- terminal. and imthis case. the: hole 22. may be of smaller: diameter,v and. again the to the form- F," either inside or outside; or both, or: within-thehole; 22- bycement or: equivalent.

By'tl iisfornxi of. take -off for the-leads for connecting the coil. S with: the external circuit; the connection is entirely independent of contact with or attachment to the diaphragm. D,. and the inner end otlthelead. atthe .forma F, partakes of the same, amplitude of. vibration. as that of the coil S due to: the reaction of. the sound-representingcurrent passing therethrough upon. the magnetic! field of theeair gap between: the inner and. outer poles I and.0,.Fig; 1.

In the; example:illustratedv in Fig; 1;. the leads L, preferably. insulatemextend outwardly from the coilform. through: a slot: er channel 812 on the under side at the plate 8; through. an opening in. the outer pole plate 0;. and thence through the aforesaid opentng .5 in: the pot P. Where: the

leadspass through the channel-1 8athey may be against the end of thefilbrm. Em tending upwardlyand inwardly from the lower end of thecylindrical portibn "17;, the spider Z I comprises the conical or equivalentl'y'shaped por I scribed in. connection In Fig. 5;. the-diaphragm D,.in: conical; or equivoverlying. outwardly turned flange" 17a and outer pole pieces I and 0 plate 0' and the housing 30 their outer ends to individually covered by pieces of rubber or other tubing, not shown, which are held or clamped between'the plate 8 and the pole plate 0, and for the diaphragm D. Here again the form of lead attachment isthat described in connection with Figs 2;- an'd the aforesaid cement is indicated at 27- asapplied onthe outside of the form F around the leadist'ructure g In. Figflf4 the diaphragm D has integrally formed therewith the coil form F. This may be done bymeuldih'g' the structure of suitable ma- .terialsuch as bakelite or the like, and, as indicated atthe right, the diaphragm may be straight,

ar -as: indicated a t the left; at 28%,.itr-n iay be grooved orchanneleda. Hereagain the lead attachment is. generality that of the character dewitltFigsa. 2 and 3..

alent form, of papen, or: other suitable. material,

-is of. large diameter for directly. acting upon the air to: produce sound waves therein. In thisfcase the'lea'd; structure is generally of the character of that hereinab'ove' described; To the col-l form F, at a. region above the. h'cl 22, thediaphragm is attached. by a; resilient-sp der structure Z of sheet aluminum or thelikerbetween whose cylindrical portion li'Z and the exterior of the form F' is held: the inwardly turned cylindriba'li flange of and at the inner'end oi! the" when, the latter of the spider structure. The spider Z in this "case is of a character for securingit. at: its center to an extension:' on the innerpolepiece generally of the character disclosed in 6-; Wlfile the.

outer pole plate 0 is shown with 'itscentral cylin drieal: aperture tanning a boundary of the air gap, the innerpole piecel is omitted for the sake ofclearness. I 1

In' Fig. 6Li's shown a embodying my invention; The. field producing means again: comprises: the pet P, core" 2, inner and exciting coil C. The bolts ofscrews- 29 secure the'outer pole for the'con'ef D to each: other; and secure the pole plate 0; on the end of the pot P. The housing 30* has at its outer and'l forward end a ring 3-1 in a; channel inwhich is held the outer" fla'nge of the member 32 of cloth or similar material glued tothe outer end of the: co'neD. overlying the aforesaid flange of the member32 is the metal or other washer 33 held to the ring 31 by the screws or rivets 34.

Overlyingthe Washer 33 and ring 31" is a felt or other suitablewasher or ring 35 which-may press against a wall of a'cabinet with the diaphragm ID in. register with the sound opening thereof; The'coil form F is-secured to'the' diaphragm D by a spring spider Z or the haract'er' illustrated in F'i'g.'-

At-its center the spider Zia-secured by screw 36 to the p 3 7"ontheouter end of inner pole piece I.

The Ieads- L are secured at the fixed terminals or binding posts 38 carried uponinsulati-ng block 39 secured to the housing Riki-and firom: these bind ing posts extend: the conductors-40 toi the source of sound-@representing; current. In. this example of my invention, as more clearly apparent from Fig 7', leads-:taake oft from pointsz rl on the coil cone-type loud-speaker Fig. l, or within jusual, the tubes, of which 1,991,221 form F, where the leads may be anchored or attached by cement or otherwise. Or, and preferably, as indicated in Fig. 7a the leadsat the point of take-off are held firmly to or anchored against the form F by cloth or adhesive tape 42 which, in

a F between the upper end of the coil S and the lower end of the cone D is sufliciently long that the points of attachment oranchorages as 41,

42, Fig. 7a, will not, at the greatest amplitude of vibration of the coil S, bring the inner portions of the leads L near or into contact with the outer pole structure 0 or any other structure necessarily adjacent thereto.

In all the arrangements described, and in similar and equivalent arrangements comprehended in my invention, the take-off of the voice coil leads is entirely independent of the diaphragm,-

and isdirectlyfromthe voice whatever its form, coil or its form; andthe inner ends of the leads at or adjacent the coil or its form partake of an amplitude of vibration amplitude of the vibration of the coil itself, as contrasted with prior structures of microphones and coil actuated diaphragms, in which the leads are attached to the diafixed terminals or bindto the external circuit phragm and take off to ing posts from'aregion on the diaphragmwhose amplitude of vibration is less than at or adjacent its center where the microphonic elements or coil is disposed.

, An electro-dynamic system of the general character herein described is effective for producing sound wavesof large amplitude when the sound-representing current traversing the. voice coil is of sufficient magnitude. This is accomplished by any suitable means, especially audio frequencyamplification by valves of the audion type. Such an arrangement, used by me and commonly in use, is indicatedin Fig.- 8 where V is a vacuum tube of the three electrode type utilized as an audio frequency amplifier upon whose input electrodes is impressed by the transformer T a sound-representing voltage derived from any or stages of audiofrequency amplification. As V is one, have their filaments or cathodes excited by current from the source A and their anode or plate circuits supplied by current from the source B. The plate circuit of the tube V is coupled to the voice coil S by the second audiofrequency transformer T1,

scribed, the combination with a diaphragm, of a application around the i the lower, portion of the tape sheet material anchoring the format a point between said coil and said dia-,

which is equal to the thereto, a voice said coil, and sheet material anchoring the lead tosaid coil form at apoint between said coil and scribed, the combination actuating the same, a

source, particularly from a prior stage coil form, a member attaching said form to said diaphragm, a voice coil on said form, a connection from said coil extending into the interior and thence to the exterior of said form, and extending therefrom independently of said diaphragm andsaid attaching memberto a fixed point. i

2. In telephonic apparatusof the character described, the combination with a conical diaphragm of large diameter, of a coil form secured thereto, a voice coil on said form, alead taking off from said form and extending independently of said diaphragm to the external circuit, and

sheet material anchoring the, format a point between said coil and said diaphragm and overlying the adjacent end of said diaphragm. e a

3. In telephonic apparatus of the character described, the combination with a conical dia- I phragm of large diameter,

of a coil form secured thereto, a voice coil on said form, a lead taking off from said form and extending independently;

of said diaphragm to the external circuit, and lead to said coil phragm and overlying diaphragm, extending from its remote edge to the lead adjacent its take-off from saidcoil form.

4. In telephonic apparatus of the character described, the combination with a conicaldiaphragm of large diameter, of

coil on said form,

the adjacent end of said a lead from said diaphragm, said lead extending independently of said diaphragm to the external circuit.

5. In telephonic apparatus of the character dewith a conical diaphragm of large diameter, of a voice coil for form on which said voice coil is disposed and which extends at substantially the diameter of member attaching said form adjacent its one end to said diaphragm, a lead extending on the outer side of said form from said coil towards said diaphragm and taking off from said form and flexiblyextending independently of said diaphragm and said attaching member to the external cir cuit, and means defining the point of take-off of said lead comprising onthe outer side of said coil form at a point between said coil and said end of said coil form.

6. In telephonic apparatus, the combination with a diaphragm, of a coil form, a voice coil on said form, a field pole plate and a pole spaced therefrom to form an air gap in which said voice coil vibrates, a spider, said coil form, spider and diaphragm united to each for connecting said coil to the external circuit,

and an anchorage for said lead comprising means securing it to said coil form independently of said spider for take off of said lead independently sa'd diaphragm.

of said spider and RUSSELL 'I. KINGSFORD.

a coil form secured said coil to said diaphragm, a

other, a flexible lead lead to said coil said sheet material having a slot 5o means anchoring said lead 

